3 replies to this topic

[Omar79]

Dear All,

Please, I ask about RVP (Reid vapor pressure) in HYSYS. How can i obtain a RVP for a Stream at 90 °F or any other temperature? Because Hysys calculate a RVP at fixed temperature 37.7 °C.

Thanks.

[Zauberberg]

You can do a trick and use heater/cooler unit operation, with process stream outlet parameters set as:

- Vapor fraction = 0
- Temperature = 90F

HYSYS will give you the pressure at which process stream is at its bubble point. If you are constrained by RVP value at 90F (by modifying upstream equipment operating parameters), then the bubble point pressure of your stream should not exceed the bubble point pressure calculated by HYSYS at given temperature.

[joerd]

That is right for TVP (total vapor pressure). RVP as defined per ASTM D323 is always at 100F (37.8C).

http://www.astm.org/Standards/D323.htm

RVP is related to TVP, and often used to limit the vapor pressure of the product, so that it can be stored in an atmospheric tank. So, Omar, can you go back and see if you need RVP (i.e. at 100F) or TVP at 90F?

[Padmakar Katre]

Dear;
How it could be the RVP as there are different methods to calculate the RVP(API and ASTM) but its always at 37.8 C.
We can use the correlation for properties selecting the Refinery and you will find RVP else you could have it with Cold Property Utility.
The best approach to get the RVP is to get it from the RVP Extension which is available free on the aspen tech support website.